High impact information on atpB

• The alga, normally tentoxin-resistant, was rendered tentoxin-sensitive by mutagenesis of its plastid atpB gene at codon 83 [1].
• The restored wild-type atpB gene remains in all transformants as an integral part of the chloroplast genome and is expressed and inherited normally [2].
• Bombardment of three mutants of the chloroplast atpB gene of Chlamydomonas reinhardtii with high-velocity tungsten microprojectiles that were coated with cloned chloroplast DNA carrying the wild-type gene permanently restored the photosynthetic capacity of the algae [2].
• The Chlamydomonas reinhardtii strain Delta26pAtE is engineered such that the atpB mRNA terminates with an mRNA destabilizing polyadenylate tract, resulting in this strain being unable to conduct photosynthesis [3].
• A collection of photosynthetic revertants was obtained from Delta26pAtE, and gel blot hybridizations revealed RNA processing alterations in the majority of these suppressor of polyadenylation (spa) strains, resulting in a failure to expose the atpB mRNA 3' poly(A) tail [3].

Biological context of atpB

• Restoration of phototrophic growth in a mutant of Chlamydomonas reinhardtii in which the chloroplast atpB gene of the ATP synthase has a deletion: an example of mitochondria-dependent photosynthesis [4].
• The region just upstream from the atpB gene in C. reinhardtii contains two small open reading frames (ORFs) and not the gene for the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase as is found in cp genomes of higher plants [5].
• No transcripts for either ORF were detected, but the codon usage in these ORFs as well as in the atpB gene follows the unique pattern of codon usage previously seen in other cp genes in C. reinhardtii [5].
• We have found that assorted other circular plasmids, single-strand DNA circles, or linear, duplex DNA molecules containing the wild-type atpB gene can also complement the same mutant [6].
• DNA gel blot hybridization analysis of all such transformants indicates that the complementing DNA has integrated into the chromosome at the atpB locus and suggests that a copy-correction mechanism operating between the inverted repeats maintains sequence identity in this region [6].

Associations of atpB with chemical compounds

• By using the atpB gene as the selected marker and cells grown in 0.5 mM 5-fluorodeoxyuridine, we have recovered up to 50 transformants per microgram of DNA [7].
• Here, we used Chlamydomonas chloroplast transformation to test the effects of mRNA homopolymer tails in vivo, with either the endogenous atpB gene or a version of green fluorescent protein developed for chloroplast expression as reporters [8].
• Catalytic properties and sensitivity to tentoxin of Chlamydomonas reinhardtii ATP synthases changed in codon 83 of atpB by site-directed mutagenesis [9].

Other interactions of atpB

• In contrast to all other cp genomes, the CF1 epsilon subunit gene (atpE) does not lie at the 3' end of the atpB gene but maps to a position 92 kb away in the other single-copy region [5].
• Cloned chloroplast DNA sequences, into which had been inserted chimeric genes composed of the GUS coding sequence reporter under transcriptional control of chloroplast promoters for the C. reinhardtii atpA, atpB, and rbcL genes, were introduced into the cells on microprojectiles [10].
• However, both the atpB and the psaB sequence data gave robust support for a rather different set of phylogenetic relationships in which neither the "pyrenoid-lost" nor the "pyrenoid-regained" clade was resolved [11].
• Incubation of synthetic RNAs corresponding to the 3' UTRs of Chlamydomonas chloroplast genes atpB and petD with a chloroplast protein extract resulted in the accumulation of stable processing products [12].
• Synthetic RNAs of the petA 3' UTR and the antisense strand of atpB 3' UTR were degraded in the extract [12].

Analytical, diagnostic and therapeutic context of atpB

• Northern analysis of total RNA and in vivo pulse labeling followed by immunoprecipitation reveals that both mutant atpB genes are transcribed and translated normally [13].
• Based on strand-specific RT-PCR, S1 nuclease protection, and RNA gel blots, evidence was obtained that the PS+ genome stabilizes atpB mRNA by generating an atpB antisense transcript, which attenuates the degradation of the polyadenylated form [3].
• Analysis of transcripts derived from chimeric atpB genes introduced into Chlamydomonas chloroplasts by biolistic transformation suggests that in vivo processing and in vitro processing occur by similar or identical mechanisms [14].
• Polypeptide products of the disrupted atpB and rbcL genes could not be detected using immunoblotting techniques [15].

References